Main Entry: tau

Pronunciation: \ˈtau̇, ˈtȯ\

Function: noun

Etymology: Middle English taw, from Latin tau, from Greek, of Semitic origin; akin to Hebrew tāw taw

Date: 14th century

1 : the 19th letter of the Greek alphabet — see alphabet table
2 : a short-lived elementary particle of the lepton family that exists in positive and negative charge states and has a mass about 3500 times greater than an electron —called also tau particle
3 : a protein that binds to and regulates the assembly and stability of neuronal microtubules and that is found in an abnormal form as the major component of neurofibrillary tangles